In general, since thermosensitive recording materials are relatively inexpensive, and recording instruments thereof are compact and are free from maintenance, the thermosensitive recording materials are broadly used. In recent years, a sales competition of thermosensitive paper has intensified, and thermosensitive recording materials are required to have higher functions that can be differentiated from conventional functions. Accordingly, the thermosensitive recording materials are extensively studied with respect to color density, image preservability, and the like.
Hitherto, 2,2-bis(4-hydroxyphenyl)propane (so-called “bisphenol A”) has been widely used as an electron-accepting compound for an electron-donating dye to be used in such thermosensitive recording materials. However, a material that is satisfactory from the viewpoints of sensitivity, background fogging prevention, image preservability, chemical resistance, anti-sticking properties, and the like has not yet been obtained.
On the other hand, Japanese Patent Application Publication (JP-B) No. 4-20792 discloses recording materials using an N-substituted sulfamoylphenol or N-substituted sulfamoylnaphthol as the electron-accepting compound and describes that the (pressure-sensitive or thermosensitive) recording materials are improved with respect to image density, image stability, and cost. However, there is room for further improvements in image density and image preservability.
Further, in cases where full-color information is recorded on thermosensitive recording materials, recording using inkjet inks is often conducted. When inkjet printing is performed on ordinary thermosensitive recording materials, colors of the inks may not be completely reproduced, and vivid colors do not appear, whereby the resulting colors become dull. It has been noted that when inkjet recording is performed on the thermosensitive recording material described in JP-B No. 4-20792, a problem arises in that the colors are dull and blackish.